Plant growth regulation compositions and methods using gibberellin biosynthesis inhibitor combinations

ABSTRACT

Described are plant growth regulation compositions and methods utilizing combinations of Class A and Class B gibberellin biosynthesis inhibitors. Preferred methods and compositions involve the combination of trinexapac-ethyl with either or both of flurprimidol and paclobutrazol, in particular to provide a synergistic effect in the regulation of the growth of turfgrass.

REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 60/436,909 filed Dec. 27, 2003, which is herebyincorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

The present invention relates generally to plant growth regulation, andin particular to plant growth regulation utilizing combinations ofactive agents that each inhibit plant gibberellin biosynthesis.

As further background, agents that accelerate or retard the rate ofgrowth of plants have been known and used in the field of turfgrass andother plant management. Agents that retard or inhibit shoot, stem andleaf elongation have traditionally been categorized by four modes ofaction. A first mode involves the inhibition of mitosis in themeristematic tissue which halts cell division and elongation. A secondmode involves a reduction of cell elongation by inhibiting or retardinggibberellin synthesis, a plant hormone needed for cell elongation. Athird mode of action involves the regulation of auxin activity andtransport, and a fourth mode involves killing terminal buds and thusreducing apical dominance.

Gibberellin synthesis inhibitors are known which act at different sitesin the biosynthetic pathway of gibberellins. Agents which act relativelylate in the synthetic pathway are known as Class A gibberellinbiosynthesis inhibitors. Trinexepac-ethyl is one such Class A agent, andis sold under the trade name Primo. Class B gibberellin biosynthesisinhibitors act relatively early in the gibberellin biosynthesis pathway.The compounds paclobutratzole and flurprimidol are known Class Bgibberellin biosynthesis inhibitors and are sold under the trade namesTrimmit and Cutless, respectively.

Growth regulation of turfgrass and other plants using high applicationrates may result in a significant waste of material, increased cost ofapplication, and the discharge of excess plant growth regulatorchemistry into the surrounding environment.

Gibberellin biosynthesis inhibitors have been used individually for sometime in the management of turfgrasses such as those occurring on golfcourses. Nonetheless, there remain needs for improved turfgrass andother plant management aspects which provide more effective resultsand/or which require lesser amounts of active agents. The presentinvention is addressed to these needs.

SUMMARY OF THE INVENTION

It has now been discovered that the use of gibberellin biosynthesisinhibitors in combination can provide more effective and efficientregulation of the growth of plants including turfgrass. This includesthe provision of synergistic combinations of gibberellin biosynthesisinhibitors, and in particular the use of at least one Class Agibberellin biosynthesis inhibitor along with at least one Class Bgibberellin biosynthesis inhibitor to achieve effective regulation ofthe growth of turfgrass or other plants.

In one embodiment of the invention, provided is a method for regulatingthe growth of a plant, and especially a turfgrass, which comprisesapplying to the plant a Class A gibberellin biosynthesis inhibitor andapplying to the plant a Class B gibberellin biosynthesis inhibitor,especially wherein the inhibitors exhibit synergism in regulating growthof the plant. Preferred Class A gibberellin biosynthesis inhibitors areencompassed by the formula:

-   -   wherein    -   A is an —OR₂ or —NR₃ R₄ radical,    -   R is C₃–C₆ cycloalkyl,    -   R₂ R₃ and R₄ are each independently hydrogen, C₁–C₆ alkyl, C₁–C₆        haloalkyl, C₂–C₁₀ alkoxyalkyl, C₂–C₁₀ alkylthioalkyl, C₃–C₆        alkenyl, which is unsubstituted or substituted by halogen, C₁–C₄        alkoxy or C₁–C₄ alkylthio; C₃–C₆ alkynyl; phenyl or C₁–C₆        aralkyl, wherein the phenyl nucleus is unsubstituted or        substituted by halogen, C₁–C₄ alkyl, C₁–C₄ alkoxy,    -   C₁–C₄ haloalkyl, nitro or cyano; one of R₃ and R₄ is methoxy; or    -   R₃ and R₄, together with the nitrogen atom to which they are        attached, form a 5- or 6-membered heterocyclic ring system which        may contain an additional oxygen or sulfur atom in the ring; and        the metal or ammonium salts thereof. A particularly preferred        such inhibitor is trinexapac-ethyl.

Some preferred Class B gibberellin biosynthesis inhibitors areencompassed by the formula:

-   -   wherein    -   R₈ is 2-pyrazinyl, 3-pyridyl, or 5-pyrimidinyl;    -   R₉ is phenyl, pyridyl, C₁–C₁₂ alkyl, or C₃–C₈ cycloalkyl;    -   R₁₀ is trifluoromethoxyphenyl, tetrafluoroethoxyphenyl,        pentafluoroethoxyphenyl, 3,4-(difluoromethylenedioxy)phenyl, or        2,2,4,4-tetrafluoro-1,3-benzodioxanyl;    -   X is hydrogen, hydroxy, lower alkoxy, lower alkylthio, or lower        alkanoyloxy;    -   or an acid addition salt thereof. A particularly preferred such        inhibitor is flurprimidol. Additional Class B gibberellin        biosynthesis inhibitors which may be used are encompassed by the        formula:

wherein

-   R₅ is alkenyl, alkynyl or optionally substituted aralkyl;-   Y is ═N— or ═CH—;-   R₆ is cycloalkyl, alkyl or haloalkyl; and-   R₇ is hydrogen, methyl or alkenyl, or an ester, an ether, an acid    addition salt or a metal complex thereof. A particularly preferred    such inhibitor is paclobutrazol.

In accordance with methods of the invention, the Class A and Class Binhibitors can be applied simultaneously to plants such as turfgrass,for example in a single tank mix; alternatively, the Class A and Class Binhibitors can be applied separately to the turfgrass or other plant,for example in rotation.

Another embodiment of the invention provides a composition forregulating plant growth that includes both a Class A gibberellinbiosynthesis inhibitor and a Class B gibberellin biosynthesis inhibitor.In preferred embodiments the inhibitor combination exhibits synergism inthe regulation of plant growth and especially in the regulation ofturfgrass growth. Particular agents within Class A and Class B includethose within the formulas noted above, and those specifically namedabove.

The present invention provides improved methods and compositions forregulating plant growth using combinations of gibberellin biosynthesisinhibitors. Additional embodiments as well as features and advantages ofthe invention will be apparent from the descriptions herein.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to certain embodiments andspecific language will be used to describe the same. It willnevertheless be understood that no limitation of the scope of theinvention is thereby intended, and alterations and modifications in theillustrated device, and further applications of the principles of theinvention as illustrated herein are contemplated as would normally occurto one skilled in the art to which the invention relates.

As disclosed above, the present invention provides methods andcompositions for regulating plant growth that involve the use of acombination of gibberellin biosynthesis inhibitors. Particularembodiments involve the use of Class A and Class B gibberellinbiosynthesis inhibitors, for example including the use oftrinexapac-ethyl(4-(Cyclopropyl-alpha-hydroxymethylene)-3,5-dioxo-cyclohexanecarboxylicacid ethyl ester) as a Class A inhibitor, and the use of flurprimidol(α-(1-methylethyl)-α-[4-(trifluoromethoxy)phenyl]-5-pyrimidinemethanol)and/or paclobutrazol((R*,R*)-β-[(4-chlorophenyl)methyl]-α-(1,1-dimethylethyl)-1H-1,2,4-triazole-1-ethanol)as a Class B gibberellin biosynthesis inhibitor.

Methods and compositions of the invention employ at least one Class Agibberellin biosynthesis inhibitor. This class of inhibitors is known tothose skilled in the art, and includes compounds which act at a latestage in the biosynthetic pathway of gibberellins, after the productionof the first gibberellic acid compound (GA₁₂), for example preventingthe conversion of GA₂₀ to GA₁. Trinexapac-ethyl and related compoundscan be used to provide the Class A gibberellin biosynthesis inhibitor.Class A inhibitors which may be used in the invention thus are describedin U.S. Pat. No. 4,693,745, and encompassed by formula:

-   -   wherein    -   A is an —OR₂ or —NR₃, R₄ radical,    -   R is C₃–C₆ cycloalkyl,    -   R₂ R₃ and R₄ are each independently hydrogen, C₁–C₆ alkyl, C₁–C₆        haloalkyl, C₂–C₁₀ alkoxyalky, C₂–C₁₀ alkylthioalkyl; C₃–C₆        alkenyl, which is unsubstituted or substituted by halogen, C₁–C₄        alkoxy or C₁–C₄ alkylthio; C₃–C₆ alkynyl; phenyl or C₁–C₆        aralkyl, wherein the phenyl nucleus is unsubstituted or        substituted by halogen, C₁–C₄ alkyl, C₁–C₄ alkoxy,    -   C₁–C₄ haloalkyl, nitro or cyano; one of R₃ and R₄ is methoxy; or    -   R₃ and R₄, together with the nitrogen atom to which they are        attached, form a 5- or 6-membered heterocyclic ring system which        may contain an additional oxygen or sulfur atom in the ring; and        the metal or ammonium salts thereof.

Trinexapac(4-(Cyclopropyl-alpha-hydroxymethylene)-3,5-dioxo-cyclohexanecarboxylicacid) and its salts or C₁–C₆ alkyl esters, including for exampletrinexapac-ethyl, are particularly preferred agents from this class.

Class B gibberellin biosynthesis inhibitors are also known to thoseskilled in the art and include compounds that act early in thebiosynthetic pathway of gibberellins. For example, Class B inhibitorsare known which interfere with the biosynthesis of gibberellic acidbefore the production of the first gibberellic acid compound, GA₁₂. GA₁₂is not only the first GA produced but is also a precursor for all otherGAs. This in effect means that GA production may be substantially slowedby the use of such Class B gibberellin biosynthesis inhibitors. A groupof such inhibitors is described in U.S. Pat. No. 4,243,405, andencompassed by the formula:

wherein

-   R₅ is alkenyl, alkynyl or optionally substituted aralkyl;-   Y is ═N— or ═CH—;-   R₆ is cycloalkyl, alkyl or haloalkyl; and-   R₇ is hydrogen, methyl or alkenyl., or an ester, an ether, an acid    addition salt or a metal complex thereof.

Another group of Class B gibberellin biosynthesis inhibitors describedin U.S. Pat. No. 4,002,628, and encompassed by the formula:

-   -   wherein    -   R₈ is 2-pyrazinyl, 3-pyridyl, or 5-pyrimidinyl;    -   R₉ is phenyl, pyridyl, C₁–C₁₂ alkyl, or C₃–C₈ cycloalkyl;    -   R₁₀ is trifluoromethoxyphenyl, tetrafluoroethoxyphenyl,        pentafluoroethoxyphenyl, 3,4-(difluoromethylenedioxy)phenyl, or        2,2,4,4-tetrafluoro-1,3-benzodioxanyl;    -   X is hydrogen, hydroxy, lower alkoxy, lower alkylthio, or lower        alkanoyloxy;    -   or an acid addition salt thereof.

In accordance with the invention, the Class A and Class B gibberellinbiosynthesis inhibitors can be used together, for example in a tank mix,or can be used separately, for example applied separately on the samedate or in rotation over time. When used together, the inhibitorcombination can be present in a composition in which they are combinedat effective concentrations and in effective ratios to achieve plantgrowth regulation. Generally, the Class A and Class B plant growthregulators will be present in a molar ratio of about 1:0.625 to about1:5 with respect to one another.

Preferably the amounts and molar ratios utilized will provide anidentifiable synergism among the compounds and the regulation of plantgrowth, in particular in the regulation of turfgrass growth. In the caseof turfgrass, this synergism may be evident in relative improvements inturf color, turf density, reduced turf scalping, growth inhibition,and/or turf quality, at any time point after application of the plantgrowth regulators. These turf characteristics are known and used bythose skilled in the art in managing turfgrass, for example turfgrassoccurring on golf courses and in particular on the fairways, puttinggreens and driving tees of golf courses which are maintained atrelatively short lengths such as 2 inches or less, with fairways moretypically being maintained at about 0.5 inch to about 1 inch, andputting greens typically being maintained at about 0.1 inch to 0.2 inch,and driving tees more typically being maintained at about 0.2 inch to0.5 inch. In one feature of the invention, it has been discovered thatthe combination of a Class A and Class B inhibitor can provide a morerapid regulation of turfgrass growth and a consequent more rapidimprovement in turf quality than either inhibitor applied alone at twicethe rate of the combination. Thus, a decreased time interval is providedbetween application of the growth regulators and the achievement ofsubstantial improvements in desirable turf characteristics.

The Class A and Class B inhibitors will be included in compositions at alevel or concentration suitable for direct application to the turfgrassor other plant from conventional spraying equipment, or suitable fordilution to prepare such a composition for direct application. Plantgrowth regulator concentrates of the invention may for example includethe Class A and Class B inhibitors each at a level of about 0.5 poundsper gallon to about 4 pounds per gallon in the case ofliquid-concentrate formulations or about 25% to 80% active ingredient inthe case of dry concentrate formulations. Such a concentrate can then bediluted with water or another solvent by a user for application to theturfgrass or other plant. The as-applied composition will contain theplant growth regulator(s) at a concentration or level suitable forapplication to the turfgrass or other plants. This may vary widelydepending upon the type of spray equipment being used, and themechanism(s) of absorption for the regulator molecule. For example,root-absorbed growth regulators such as paclobutrazol and flurprimidolare usually applied in relatively high volume spray systems, and thuscan be included in as-applied liquid at relatively low concentrations.Foliar-absorbed growth regulators such as trinexapac-ethyl may beapplied in relatively low volume spray systems to minimize run off fromthe foliage, and thus may be commonly included in the as-applied liquidat relatively higher concentrations. When applying a combination of aroot-absorbed (paclobutrazol or flurprimidol) and a foliar-absorbedregulator (trinexapac-ethyl), strategies may be adopted to facilitateeffective uptake of the chemicals. For example, the two growthregulators may be applied separately under conditions conducive to theirmode of uptake. On the other hand, they may also be applied togetherwhile achieving suitable uptake of each. For example, in one mode ofapplication, the root-absorbed and foliar-absorbed regulators can beapplied together with a low-volume spray system, to minimize run-off andallow for the foliar uptake of the foliar-absorbed regulator. After aresidence time, e.g. 0.5 to about 24 hours, the turfgrass or other plantarea can then be watered, to move the root-absorbed regulator to theplant roots for absorption. These and other suitable modes ofapplication of the growth regulator combination will be apparent tothose skilled in the art given the teachings herein.

As to application rate, this will vary depending on the plant to betreated and suitable application rates for plant growth regulators areused herein or can be determined using routine experimentation.Generally, when treating turfgrass, the Class A gibberellin biosynthesisinhibitor, such as trinexapac-ethyl, will be applied at a rate about0.02 to about 0.7 pounds of active ingredient per acre. Class Bgibberellin biosynthesis inhibitors will generally be applied at a rateof about 0.05 to about 1.5 pounds of active ingredient per acre. Forexample, flurprimidol will typically be applied at a rate in the rangeof about 0.05 to about 1.5 pounds of active ingredient per acre, andpaclobutrazol will typically be applied at a rate in the range of about0.05 to about 1.0 pounds of active ingredient per acre. These rates maybe used when applying the inhibitors separately (e.g. in rotation) orwhen applying the inhibitors together. When applying the inhibitors inrotation, it will desirable to apply the two inhibitors within aboutfour weeks of one another, although shorter or longer times may also beused within the scope of the present invention. In one mode ofoperation, the two active ingredients can be applied at times and underconditions wherein effective growth regulating amounts of each arepresent in the plant.

Turfgrass species that can be growth regulated in accordance with theinvention include, for example, warm-season species such as Bahiagrass(Paspalum notatum); Bermudagrass (Cynodon dactylon); Buffalograss(Buchloe dactyloides); Carpetgrass (Axonopus affinis); Centipedegrass(Eremochloa ophiuroides); Kikuyugrass (Pennisetum cladestinum); Seashorepaspalum (Paspalum vaginatum); St. Augustinegrass (Stenotaphrumsecundatum); Zoysiagrass (Zoysia matrella (japonica)); cool-seasonspecies such as Annual ryegrass (Lolium multiflorum); Bentgrass(Agrostis spp.); Fescue (Festuca spp.); Kentucky bluegrass (Poapratensis); Perennial ryegrass (Lolium perenne); Bentgrass/Poa annuamixtures; Kentucky bluegrass/Fescue/Ryegrass mixtures; and Kentuckybluegrass/ryegrass/Poa annua mixtures. Preferred turfgrasses to becontrolled in the invention include Bermudagrass (Cynodon dactylon);Annual ryegrass (Lolium multiflorum); Bentgrass (Agrostis spp.);Kentucky bluegrass (Poa pratensis); and Perennial ryegrass (Loliumperenne).

Gibberellin biosynthesis inhibitors used in the invention can becombined with suitable liquid carriers to form liquid compositions. Anysuitable carrier may be used, including those consisting essentially ofwater, or those including organic solvents such as alcohols, e.g.ethanol, liquid fertilizer formulations, or mixtures thereof. Water orother aqueous carriers are preferred.

Additional formulation adjuvants can be present as is conventional inthe field. Typically, these will be included at levels up to about 30percent by weight of the composition, more often at levels not exceedingabout 20 percent by weight of the composition. Such adjuvants may forexample include one or more surface-active agents. Potential surfaceactive agents include the alkali, alkaline earth and ammonium salts ofaromatic sulfonic acids, such as lignin-, phenol-, naphthalene-, anddibutylnaphthalenesulfonic acid, as well as those of fatty acids, alkyland alkylaryl sulfonates, alkyllaurel ether and fatty alcohol sulfates,and salts of sulfated hexa-, hepta- and octadecanols or fatty alcoholglycol ethers, condensation products of sulfonated naphthalene and itsderivatives with formaldehyde, condensation products of naphthalene ornaphthalenesulfonic acids with phenol and formaldehyde, polyoxyethyleneoctyl phenol ether, ethoxylated isooctyl, octyl or nonylphenol,alkylphenol or tributylphenyl polyglycol ether, alkylaryl polyetheralcohols, isotridecyl alcohol, fatty-alcohol ethylene oxide condensates,ethoxylated castor oil, polyoxyethylene alkyl ether or polyoxypropylene,lauryl alcohol polyglycol ether acetate, sorbitol ester, lignin sulfitewaste liquors, or methylcellulose. The resulting liquid formulation maybe a solution, suspension, emulsion (including microemulsions), or anyother suitable form known in the art.

For the purpose of promoting a further understanding of the presentinvention and its features and advantages, the following specificExamples are provided. It will be understood that these Examples areillustrative, and not limiting, of the invention.

EXAMPLE 1

Tifsport Bermudagrass growing on a nursery area in South Carolina wastreated with Cutless 50W (Cutless) and Primo Maxx 1EC (Primo) eithersingly or tank mixed to determine growth regulator activity. Cutless 50Wis a commercially available product containing flurprimidol. Primo Maxxis a commercially available product containing trinexapac-ethyl. Primowas applied alone at 0.05 and 0.1 pound of active ingredient per acre(LB AI/A), Cutless was applied alone at 0.125 and 0.25 LB AI/A, andPrimo+Cutless were applied at 0.05+0.125 and 0.1+0.25 LB AI/A. Plot sizewas 6′×12′ with four replications. Three applications with a CO₂back-pack sprayer were made, occurring on May 29, June 27 and July 29.Plots received approximately 0.25 inches of irrigation on each treatmentdate within 8 hours but not sooner than 4 hours after treatment. Ratingsto evaluate performance included injury (0–10 with 0=No injury,10=Death), color (plus or minus 100 with 100=Color of untreated, plus100=Darker green than untreated, minus 100=Lighter green thanuntreated), density (DENS) (0–10 with 0=Bare ground, 10=Maximumpotential density), quality (QUAL) (0–9 with 0=Poor quality, 9=Maximumpotential quality), growth inhibition (GRINHIB) (percentage estimated),and scalping (CUT) (percentage estimated). The results are presented inTable 1. The following abbreviations are used in Table 1 and in theother Tables presented in these Examples: AI/A=active ingredient peracre; DAAA=Days after application; LB=pounds. Means followed by the sameletter do not significantly differ (P=0.05, Duncan's New MRT).

TABLE 1 Evaluation Date 13Jun02 13Jun02 13Jun02 13Jun02 20Jun02Evaluation Type* COLOR DENS QUAL CUT COLOR Eval Unit/Scale* % VISUAL0–10 0–9SCAL % VISUAL % VISUAL Trt-Eval Interval 15DAAA SCAL 15DAAA15DAAA 22DAAA Footnote No. 15DAAA PRM Data Type* Trt Appl Treatment FormFm Ra Timing/ No Code Name* Conc Ds* Rate Un* Dev Stg 1 A PRIMO 1 EC0.05 LB AI/A JUNE 117.5 ab 9.13 ab 8.50 a 6.3 d 117.5 ab A CUTLESS 50 WP0.125 LB AI/A JUNE B PRIMO 1 EC 0.05 LB AI/A JULY B CUTLESS 50 WP 0.125LB AI/A JULY C PRIMO 1 EC 0.05 LB AI/A AUGUST C CUTLESS 50 WP 0.125 LBAI/A AUGUST 2 A PRIMO 1 EC 0.1 LB AI/A JUNE 122.5 a 9.63 a 7.88 a 2.5 d122.5 a A CUTLESS 50 WP 0.25 LB AI/A JUNE B PRIMO 1 EC 0.1 LB AI/A JULYB CUTLESS 50 WP 0.25 LB AI/A JULY C PRIMO 1 EC 0.1 LB AI/A AUGUST CCUTLESS 50 WP 0.25 LB AI/A AUGUST 3 A PRIMO 1 EC 0.05 LB AI/A JUNE 100.0d 6.88 e 6.13 b 57.5 a 101.3 c B PRIMO 1 EC 0.05 LB AI/A JULY C PRIMO 1EC 0.05 LB AI/A AUGUST 4 A PRIMO 1 EC 0.1 LB AI/A JUNE 108.8 c 8.00 cd7.50 ab 35.0 bc 111.3 b B PRIMO 1 EC 0.1 LB AI/A JULY C PRIMO 1 EC 0.1LB AI/A AUGUST 5 A CUTLESS 50 WP 0.125 LB AI/A JUNE 106.3 cd 7.75 d 7.38ab 20.0 cd 101.3 c B CUTLESS 50 WP 0.125 LB AI/A JULY C CUTLESS 50 WP0.125 LB AI/A AUGUST 6 A CUTLESS 50 WP 0.25 LB AI/A JUNE 115.0 b 8.63 bc8.07 a 11.3 d 111.3 b B CUTLESS 50 WP 0.25 LB AI/A JULY C CUTLESS 50 WP0.25 LB AI/A AUGUST 70 UNTREATED 100.0 d 6.25 e 6.00 b 47.5 ab 100.0 cLSD (P = .05) 6.15 0.772 1.449 17.87 6.31 CV 3.77 6.46 13.27 46.79 3.89Replicate F 1.526 0.485 0.077 1.398 0.923 Replicate Prob (F) 0.24190.6967 0.9718 0.2757 0.4497 Treatment F 17.601 21.441 3.836 12.57817.176 Treatment Prob (F) 0.0001 0.0001 0.0122 0.0001 0.0001 EvaluationDate 20Jun02 20Jun02 27Jun02 27Jun02 27Jun02 Evaluation Type* DENS QUALCOLOR DENS QUAL Eval Unit/Scale* 0–10 0–9SCAL % VISUAL 0–10 0–9SCALTrt-Eval Interval SCAL 15DAAA 29DAAA SCAL 29DAAA Footnote No. 15DAAA29DAAA PRM Data Type* Trt Appl Treatment Form Fm Ra Timing/ No CodeName* Conc Ds* Rate Un* Dev Stg 1 A PRIMO 1 EC 0.05 LB AI/A JUNE 9.1 ab8.4 a 102.5 8.1 b 8.0 b A CUTLESS 50 WP 0.125 LB AI/A JUNE cd B PRIMO 1EC 0.05 LB AI/A JULY B CUTLESS 50 WP 0.125 LB AI/A JULY C PRIMO 1 EC0.05 LB AI/A AUGUST C CUTLESS 50 WP 0.125 LB AI/A AUGUST 2 A PRIMO 1 EC0.1 LB AI/A JUNE 9.9 a 8.8 a 118.8 a 9.6 a 8.9 a A CUTLESS 50 WP 0.25 LBAI/A JUNE B PRIMO 1 EC 0.1 LB AI/A JULY B CUTLESS 50 WP 0.25 LB AI/AJULY C PRIMO 1 EC 0.1 LB AI/A AUGUST C CUTLESS 50 WP 0.25 LB AI/A AUGUST3 A PRIMO 1 EC 0.05 LB AI/A JUNE 7.4 d 6.9 c 98.8 d 7.3 c 7.1 d B PRIMO1 EC 0.05 LB AI/A JULY C PRIMO 1 EC 0.05 LB AI/A AUGUST 4 A PRIMO 1 EC0.1 LB AI/A JUNE 8.4 bc 7.8 b 105.0 c 8.1 b 7.5 cd B PRIMO 1 EC 0.1 LBAI/A JULY C PRIMO 1 EC 0.1 LB AI/A AUGUST 5 A CUTLESS 50 WP 0.125 LBAI/A JUNE 7.6 cd 7.3 bc 100.0 d 7.3 c 7.1 d B CUTLESS 50 WP 0.125 LBAI/A JULY C CUTLESS 50 WP 0.125 LB AI/A AUGUST 6 A CUTLESS 50 WP 0.25 LBAI/A JUNE 8.4 bc 7.6 b 108.8 b 8.5 b 7.9 bc B CUTLESS 50 WP 0.25 LB AI/AJULY C CUTLESS 50 WP 0.25 LB AI/A AUGUST 70 UNTREATED 6.4 e 6.1 d 100.0d 7.3 c 7.1 d LSD (P = .05) 0.789 0.587 3.74 0.504 0.456 CV 6.5 5.23 2.44.23 4.01 Replicate F 0.877 4.935 0.891 3.595 0.853 Replicate Prob (F)0.4715 0.0113 0.4649 0.0340 0.4833 Treatment F 19.056 20.099 31.31326.690 17.842 Treatment Prob (F) 0.0001 0.0001 0.0001 0.0001 0.0001Evaluation Date 09Jul02 09Jul02 09Jul02 09Jul02 29Jul02 Evaluation Type*COLOR DENS QUAL CUT COLOR Eval Unit/Scale* % VISUAL 0–10 0–9SCAL %VISUAL % VISUAL Trt-Eval Interval 29DAAA SCAL 29DAAA 12DAAA 32DAAA29DAAA Trt Appl Treatment Form Fm Ra Timing/ No Code Name* Conc Ds* RateUn* Dev Stg 1 A PRIMO 1 EC 0.05 LB AI/A JUNE 125.0 b 10.0 a 9.0 a 0.0 c107.5 bc A CUTLESS 50 WP 0.125 LB AI/A JUNE B PRIMO 1 EC 0.05 LB AI/AJULY B CUTLESS 50 WP 0.125 LB AI/A JULY C PRIMO 1 EC 0.05 LB AI/A AUGUSTC CUTLESS 50 WP 0.125 LB AI/A AUGUST 2 A PRIMO 1 EC 0.1 LB AI/A JUNE132.5 a 10.0 a 9.0 a 0.0 c 119.5 a A CUTLESS 50 WP 0.25 LB AI/A JUNE BPRIMO 1 EC 0.1 LB AI/A JULY B CUTLESS 50 WP 0.25 LB AI/A JULY C PRIMO 1EC 0.1 LB AI/A AUGUST C CUTLESS 50 WP 0.25 LB AI/A AUGUST 3 A PRIMO 1 EC0.05 LB AI/A JUNE 105.0 e 7.5 d 7.1 d 15.0 b 98.8 c B PRIMO 1 EC 0.05 LBAI/A JULY C PRIMO 1 EC 0.05 LB AI/A AUGUST 4 A PRIMO 1 EC 0.1 LB AI/AJUNE 111.3 d 8.3 c 7.8 c 5.0 bc 101.3 bc B PRIMO 1 EC 0.1 LB AI/A JULY CPRIMO 1 EC 0.1 LB AI/A AUGUST 5 A CUTLESS 50 WP 0.125 LB AI/A JUNE 105.0e 7.5 d 7.1 d 7.5 bc 100.0 c B CUTLESS 50 WP 0.125 LB AI/A JULY CCUTLESS 50 WP 0.125 LB AI/A AUGUST 6 A CUTLESS 50 WP 0.25 LB AI/A JUNE116.3 c 8.9 b 8.1 b 0.0 c 110.0 b B CUTLESS 50 WP 0.25 LB AI/A JULY CCUTLESS 50 WP 0.25 LB AI/A AUGUST 70 UNTREATED 100.0 f 6.5 e 5.9 e 40.0100.0 c LSD (P = .05) 2.61 0.456 0.310 10.59 8.58 CV 1.54 3.67 2.7173.91 5.48 Replicate F 0.774 0.853 1.636 1.383 1.254 Replicate Prob (F)0.5235 0.4833 0.2162 0.2801 0.3197 Treatment F 180.484 74.937 115.36416.477 6.880 Treatment Prob (F) 0.0001 0.0001 0.0001 0.0001 0.0006Evaluation Date 29Jul02 29Jul02 29Jul02 29Jul02 Evaluation Type* DENSQUAL GRINHIB CUT Eval Unit/Scale* 0–10 0–9SCAL % VISUAL % VISUALTrt-Eval Interval SCAL 32DAAA 32DAAA 32DAAA 32DAAA Trt Appl TreatmentForm Fm Ra Timing/ No Code Name* Conc Ds* Rate Un* Dev Stg 1 A PRIMO 1EC 0.05 LB AI/A JUNE 7.6 b 7.4 b 13.8 b 13.8 cd A CUTLESS 50 WP 0.125 LBAI/A JUNE B PRIMO 1 EC 0.05 LB AI/A JULY B CUTLESS 50 WP 0.125 LB AI/AJULY C PRIMO 1 EC 0.05 LB AI/A AUGUST C CUTLESS 50 WP 0.125 LB AI/AAUGUST 2 A PRIMO 1 EC 0.1 LB AI/A JUNE 9.5 a 8.6 a 28.8 a 0.0 e ACUTLESS 50 WP 0.25 LB AI/A JUNE B PRIMO 1 EC 0.1 LB AI/A JULY B CUTLESS50 WP 0.25 LB AI/A JULY C PRIMO 1 EC 0.1 LB AI/A AUGUST C CUTLESS 50 WP0.25 LB AI/A AUGUST 3 A PRIMO 1 EC 0.05 LB AI/A JUNE 6.3 cd 5.8 de 0.0 d25.0 b B PRIMO 1 EC 0.05 LB AI/A JULY C PRIMO 1 EC 0.05 LB AI/A AUGUST 4A PRIMO 1 EC 0.1 LB AI/A JUNE 6.5 cd 5.9 de 5.0 cd 21.3 bc B PRIMO 1 EC0.1 LB AI/A JULY C PRIMO 1 EC 0.1 LB AI/A AUGUST 5 A CUTLESS 50 WP 0.125LB AI/A JUNE 7.1 bc 6.5 cd 3.8 cd 11.3 cd B CUTLESS 50 WP 0.125 LB AI/AJULY C CUTLESS 50 WP 0.125 LB AI/A AUGUST 6 A CUTLESS 50 WP 0.25 LB AI/AJUNE 7.6 b 7.1 bc 10.0 bc 6.3 de B CUTLESS 50 WP 0.25 LB AI/A JULY CCUTLESS 50 WP 0.25 LB AI/A AUGUST 70 UNTREATED 5.6 5.3 0.0 36.3 LSD (P =.05) 0.855 0.802 6.38 10.58 CV 8.02 8.13 49.09 43.82 Replicate F 1.0420.571 1.339 3.164 Replicate Prob (F) 0.3979 0.6410 0.2931 0.0498Treatment F 19.168 18.388 22.355 11.795 Treatment Prob (F) 0.0001 0.00010.0001 0.0001 Evaluation Date 29Jul02 14Aug02 14Aug02 14Aug02 EvaluationType* COLOR DENS QUAL GRINHIB Eval Unit/Scale* % VISUAL % VISUAL 0–9SCAL% VISUAL Trt-Eval Interval 32DAAA 16DAAA 16DAAA 16DAAA Trt ApplTreatment Form Fm Ra Timing/ No Code Name* Conc Ds* Rate Un* Dev Stg 1 APRIMO 1 EC 0.05 LB AI/A JUNE 125.0 a 9.8 a 8.8 a 15.0 b A CUTLESS 50 WP0.125 LB AI/A JUNE B PRIMO 1 EC 0.05 LB AI/A JULY B CUTLESS 50 WP 0.125LB AI/A JULY C PRIMO 1 EC 0.05 LB AI/A AUGUST C CUTLESS 50 WP 0.125 LBAI/A AUGUST 2 A PRIMO 1 EC 0.1 LB AI/A JUNE 120.0 a 9.1 a 8.4 a 21.3 a ACUTLESS 50 WP 0.25 LB AI/A JUNE B PRIMO 1 EC 0.1 LB AI/A JULY B CUTLESS50 WP 0.25 LB AI/A JULY C PRIMO 1 EC 0.1 LB AI/A AUGUST C CUTLESS 50 WP0.25 LB AI/A AUGUST 3 A PRIMO 1 EC 0.05 LB AI/A JUNE 103.8 bc 7.6 b 7.3b 3.8 cd B PRIMO 1 EC 0.05 LB AI/A JULY C PRIMO 1 EC 0.05 LB AI/A AUGUST4 A PRIMO 1 EC 0.1 LB AI/A JUNE 108.8 bc 8.1 b 7.8 b 8.8 c B PRIMO 1 EC0.1 LB AI/A JULY C PRIMO 1 EC 0.1 LB AI/A AUGUST 5 A CUTLESS 50 WP 0.125LB AI/A JUNE 105.0 bc 7.6 b 7.3 b 6.3 c B CUTLESS 50 WP 0.125 LB AI/AJULY C CUTLESS 50 WP 0.125 LB AI/A AUGUST 6 A CUTLESS 50 WP 0.25 LB AI/AJUNE 110.0 b 8.0 b 7.5 b 15.0 b B CUTLESS 50 WP 0.25 LB AI/A JULY CCUTLESS 50 WP 0.25 LB AI/A AUGUST 70 UNTREATED 100.0 c 6.6 c 6.3 c 0.0 dLSD (P = .05) 10.58 6.12 0.619 5.58 CV 43.82 3.73 5.49 37.53 Replicate F3.164 0.632 0.600 0.507 Replicate Prob (F) 0.0498 0.6041 0.6233 0.6824Treatment F 11.795 19.246 15.446 15.676 Treatment Prob (F) 0.0001 0.00010.0001 0.0001

Evaluations made 13 days after the May 29 application showedsignificantly (P=0.05, Duncan's New MRT), better color, density andscalping reduction with Primo+Cutless tank mixed at 0.05+0.125 LB AI/Athan Primo alone at 0.1 LB AI/A. There was no significant differencebetween Cutless applied alone at 0.25 LB AI/A and the tank mix on thisobservation date. By 29 days after the first application, the differencenoted above had disappeared and the low rate tank mix treatment was notsuperior to either material applied alone at two times (2×) therespective tank mix rates.

By 12 days after the June 27 application, the low rate tank mix gavesignificantly better color, density and quality compared with eithermaterial applied alone at 2× the respective tank mix rates. The tank mixtreatment continued to show better density, quality and overall growthinhibition compared with Primo alone at 0.1 LB AI/A 32 days after thesecond application. Cutless at 0.25 LB AI/A performed similar to the lowrate tank mix on this date.

Ratings 16 days after the July 29 application showed that the low ratetank mix provided significantly better color, density and quality thaneither Cutless or Primo applied alone at 2× the respective tank mixrates.

In summary, Primo+Cutless applied to Tifsport Bermudagrass at 0.05+0.125LB AI/A provided significantly better turf color, density and qualitythan either material applied alone at 2× the respective tank mix rates(Primo 0.1, Cutless 0.25 LB AI/A) in ratings made 12 to 16 days afterapplication. Differences between tank mix and single treatments largelydisappeared by 29 to 32 days after application. This trial indicatesthat tank mix applications of Primo+Cutless at rates substantially lowerthan those recommended for either material applied alone will providegood turfgrass color, density and quality, and lead to more rapidregulation and improvement of the turfgrass than either activeingredient applied alone at 2× the respective tank mix rates.

EXAMPLE 2

Tifway (419) Bermudagrass growing under fairway conditions in SouthCarolina was treated with Cutless 50W and Primo Maxx lEC either singlyor tank mixed to determine growth regulator activity. Primo was appliedalone at 0.05 and 0.1 LB AI/A, Cutless was applied alone at 0.125 and0.25 LB AI/A, and Primo+Cutless were applied at 0.05+0.125 and 0.1+0.25LB AI/A. Plot size was 6′×12′ with four replications. Three applicationswith a CO₂ back-pack sprayer were made, occurring on May 29, June 27 andJuly 29. Plots received approximately 0.25 inches of irrigation on eachtreatment date within 8 hours but not sooner than 4 hours aftertreatment. Ratings to evaluate performance have included injury (0–10with 0=No injury, 10=Death), color (plus or minus 100 with 100=Color ofuntreated, plus 100=Darker green than untreated, minus 100=Lighter greenthan untreated), density (0–10 with 0=Bare ground, 10=Maximum potentialdensity), quality (0–9 with 0=Poor quality, 9=Maximum potentialquality), growth inhibition (percentage estimated), and scalping(percentage estimated). The results are presented in Table 2 below.

TABLE 2 Evaluation Date 09Jun02 09Jun02 09Jun02 09Jun02 Evaluation Type*COLOR DENS QUAL CUT Eval Unit/Scale* % VISUAL 0–10SCAL 0–9SCAL % VISUALTrt-Eval Interval 11DAAA 11DAAA 11DAAA 11DAAA Trt Appl Treatment Form FmRa Timing/ No Code Name* Conc Ds* Rate Un* Dev Stg 1 A PRIMO 1 EC 0.05LB AI/A JUNE 98.8 a 10.00 a 8.75 a 0.0 a A CUTLESS 50 WP 0.125 LB AI/AJUNE B PRIMO 1 EC 0.05 LB AI/A JULY B CUTLESS 50 WP 0.125 LB AI/A JULY CPRIMO 1 EC 0.05 LB AI/A AUGUST C CUTLESS 50 WP 0.125 LB AI/A AUGUST 2 APRIMO 1 EC 0.1 LB AI/A JUNE 99.0 a 9.95 a 8.88 a 0.0 a A CUTLESS 50 WP0.25 LB AI/A JUNE B PRIMO 1 EC 0.1 LB AI/A JULY B CUTLESS 50 WP 0.25 LBAI/A JULY C PRIMO 1 EC 0.1 LB AI/A AUGUST C CUTLESS 50 WP 0.25 LB AI/AAUGUST 3 A PRIMO 1 EC 0.05 LB AI/A JUNE 97.5 ab 9.75 a 8.68 a 0.0 a BPRIMO 1 EC 0.05 LB AI/A JULY C PRIMO 1 EC 0.05 LB AI/A AUGUST 4 A PRIMO1 EC 0.1 LB AI/A JUNE 93.3 b 9.75 a 8.38 a 0.0 a B PRIMO 1 EC 0.1 LBAI/A JULY C PRIMO 1 EC 0.1 LB AI/A AUGUST 5 A CUTLESS 50 WP 0.125 LBAI/A JUNE 98.8 a 9.70 a 8.80 a 0.0 a B CUTLESS 50 WP 0.125 LB AI/A JULYC CUTLESS 50 WP 0.125 LB AI/A AUGUST 6 A CUTLESS 50 WP 0.25 LB AI/A JUNE99.5 a 9.88 a 8.80 a 0.0 a B CUTLESS 50 WP 0.25 LB AI/A JULY C CUTLESS50 WP 0.25 LB AI/A AUGUST 7 UNTREATED 100.0 a 9.63 a 8.63 a 0.0 a LSD (P= .05) 4.80 0.360 0.461 0.00 CV 3.3 2.47 3.57 0.0 Replicate F 0.8962.990 0.356 0.000 Replicate Prob (F) 0.4622 0.0584 0.7854 1.0000Treatment F 1.984 1.286 1.140 0.000 Treatment Prob (F) 0.1215 0.31270.3794 1.0000 Evaluation Date 14Jun02 14Jun02 14Jun02 14Jun02 EvaluationType* COLOR DENS QUAL CUT Eval Unit/Scale* % VISUAL 0–10SCAL 0–9SCAL %VISUAL Trt-Eval Interval 16DAAA 16DAAA 11DAAA 16DAAA Trt Appl TreatmentForm Fm Ra Timing/ No Code Name* Conc Ds* Rate Un* Dev Stg 1 A PRIMO 1EC 0.05 LB AI/A JUNE 116.3 a 9.38 a 8.70 ab 0.0 d A CUTLESS 50 WP 0.125LB AI/A JUNE B PRIMO 1 EC 0.05 LB AI/A JULY B CUTLESS 50 WP 0.125 LBAI/A JULY C PRIMO 1 EC 0.05 LB AI/A AUGUST C CUTLESS 50 WP 0.125 LB AI/AAUGUST 2 A PRIMO 1 EC 0.1 LB AI/A JUNE 120.0 a 9.50 a 8.75 a 1.3 cd ACUTLESS 50 WP 0.25 LB AI/A JUNE B PRIMO 1 EC 0.1 LB AI/A JULY B CUTLESS50 WP 0.25 LB AI/A JULY C PRIMO 1 EC 0.1 LB AI/A AUGUST C CUTLESS 50 WP0.25 LB AI/A AUGUST 3 A PRIMO 1 EC 0.05 LB AI/A JUNE 102.5 bc 8.38 b8.13 cd 7.5 a B PRIMO 1 EC 0.05 LB AI/A JULY C PRIMO 1 EC 0.05 LB AI/AAUGUST 4 A PRIMO 1 EC 0.1 LB AI/A JUNE 115.0 a 9.00 ab 8.38 bc 3.8 bc BPRIMO 1 EC 0.1 LB AI/A JULY C PRIMO 1 EC 0.1 LB AI/A AUGUST 5 A CUTLESS50 WP 0.125 LB AI/A JUNE 107.5 b 8.50 b 8.38 bc 6.3 ab B CUTLESS 50 WP0.125 LB AI/A JULY C CUTLESS 50 WP 0.125 LB AI/A AUGUST 6 A CUTLESS 50WP 0.25 LB AI/A JUNE 118.8 a 9.38 a 8.57 ab 0.0 d B CUTLESS 50 WP 0.25LB AI/A JULY C CUTLESS 50 WP 0.25 LB AI/A AUGUST 7 UNTREATED 100.0 c8.38 b 7.88 d 8.8 a LSD (P = .05) 5.94 0.678 0.319 3.17 CV 3.59 5.112.56 54.38 Replicate F 1.043 9.600 13.807 1.304 Replicate Prob (F)0.3973 0.0005 0.0001 0.3036 Treatment F 16.230 4.886 8.586 11.609Treatment Prob (F) 0.0001 0.0040 0.0002 0.0001 Evaluation Date 27Jun0227Jun02 27Jun02 10Jul02 Evaluation Type* COLOR DENS QUAL COLOR EvalUnit/Scale* % VISUAL 0–10SCAL 0–9SCAL % VISUAL Trt-Eval Interval 29DAAA29DAAA 29DAAA 13DAAA Trt Appl Treatment Form Fm Ra Timing/ No Code Name*Conc Ds* Rate Un* Dev Stg 1 A PRIMO 1 EC 0.05 LB AI/A JUNE 106.3 b 8.13b 7.88 b 116.3 b A CUTLESS 50 WP 0.125 LB AI/A JUNE B PRIMO 1 EC 0.05 LBAI/A JULY B CUTLESS 50 WP 0.125 LB AI/A JULY C PRIMO 1 EC 0.05 LB AI/AAUGUST C CUTLESS 50 WP 0.125 LB AI/A AUGUST 2 A PRIMO 1 EC 0.1 LB AI/AJUNE 120.0 a 9.50 a 9.25 a 121.3 a A CUTLESS 50 WP 0.25 LB AI/A JUNE BPRIMO 1 EC 0.1 LB AI/A JULY B CUTLESS 50 WP 0.25 LB AI/A JULY C PRIMO 1EC 0.1 LB AI/A AUGUST C CUTLESS 50 WP 0.25 LB AI/A AUGUST 3 A PRIMO 1 EC0.05 LB AI/A JUNE 101.3 c 7.50 cd 7.38 bc 105.0 d B PRIMO 1 EC 0.05 LBAI/A JULY C PRIMO 1 EC 0.05 LB AI/A AUGUST 4 A PRIMO 1 EC 0.1 LB AI/AJUNE 107.5 b 8.00 bc 7.88 b 110.0 c B PRIMO 1 EC 0.1 LB AI/A JULY CPRIMO 1 EC 0.1 LB AI/A AUGUST 5 A CUTLESS 50 WP 0.125 LB AI/A JUNE 100.0c 7.00 de 7.13 c 101.3 e B CUTLESS 50 WP 0.125 LB AI/A JULY C CUTLESS 50WP 0.125 LB AI/A AUGUST 6 A CUTLESS 50 WP 0.25 LB AI/A JUNE 108.8 b 8.00bc 7.75 b 112.5 c B CUTLESS 50 WP 0.25 LB AI/A JULY C CUTLESS 50 WP 0.25LB AI/A AUGUST 7 UNTREATED 100.0 c 6.63 e 6.25 100.0 e LSD (P = .05)4.58 0.575 0.521 3.10 CV 2.9 4.95 4.59 1.91 Replicate F 0.344 0.3974.839 0.205 Replicate Prob (F) 0.7940 0.7565 0.0122 0.8919 Treatment F21.000 23.066 27.000 56.727 Treatment Prob (F) 0.0001 0.0001 0.00010.0001 Evaluation Date 10Jul02 10Jul02 29Jul02 29Jul02 29Jul02Evaluation Type* DENS QUAL COLOR DENS QUAL Eval Unit/Scale* 0–10SCAL0–9SCAL % VISUAL 0–10SCAL 0–9SCAL Trt-Eval Interval 13DAAA 13DAAA 32DAAA32DAAA 32DAAA Trt Appl Treatment Form Fm Ra Timing/ No Code Name* ConcDs* Rate Un* Dev Stg 1 A PRIMO 1 EC 0.05 LB AI/A JUNE 8.63 b 7.88 b108.8 b 8.25 b 7.75 ab A CUTLESS 50 WP 0.125 LB AI/A JUNE B PRIMO 1 EC0.05 LB AI/A JULY B CUTLESS 50 WP 0.125 LB AI/A JULY C PRIMO 1 EC 0.05LB AI/A AUGUST C CUTLESS 50 WP 0.125 LB AI/A AUGUST 2 A PRIMO 1 EC 0.1LB AI/A JUNE 9.63 a 8.63 a 116.3 a 9.00 a 8.25 a A CUTLESS 50 WP 0.25 LBAI/A JUNE B PRIMO 1 EC 0.1 LB AI/A JULY B CUTLESS 50 WP 0.25 LB AI/AJULY C PRIMO 1 EC 0.1 LB AI/A AUGUST C CUTLESS 50 WP 0.25 LB AI/A AUGUST3 A PRIMO 1 EC 0.05 LB AI/A JUNE 7.38 cd 6.88 d 100.0 c 7.50 c 7.00 cd BPRIMO 1 EC 0.05 LB AI/A JULY C PRIMO 1 EC 0.05 LB AI/A AUGUST 4 A PRIMO1 EC 0.1 LB AI/A JUNE 7.38 cd 7.13 cd 102.5 c 7.50 c 7.38 bc B PRIMO 1EC 0.1 LB AI/A JULY C PRIMO 1 EC 0.1 LB AI/A AUGUST 5 A CUTLESS 50 WP0.125 LB AI/A JUNE 7.00 de 6.88 d 101.3 c 7.50 c 7.13 cd B CUTLESS 50 WP0.125 LB AI/A JULY C CUTLESS 50 WP 0.125 LB AI/A AUGUST 6 A CUTLESS 50WP 0.25 LB AI/A JUNE 7.88 c 7.50 bc 107.5 b 8.13 b 7.75 ab B CUTLESS 50WP 0.25 LB AI/A JULY C CUTLESS 50 WP 0.25 LB AI/A AUGUST 7 UNTREATED6.63 6.25 100.0 c 7.13 6.63 d LSD (P = .05) 0.667 0.515 3.56 0.502 0.529CV 5.76 4.74 2.28 4.3 4.81 Replicate F 2.483 4.240 0.155 0.209 0.070Replicate Prob (F) 0.0938 0.0197 0.9250 0.8890 0.9751 Treatment F 21.17720.107 25.138 14.322 9.469 Treatment Prob (F) 0.0001 0.0001 0.00010.0001 0.0001

Evaluations 11 and 16 days after the May 29 application showed nosignificant differences (P=0.05, Duncan's New MRT) in color, density,quality and scalping reduction with Primo+Cutless tank mixed at0.05+0.125 LB AI/A than with Primo or Cutless alone at 0.1 and 0.25 LBAI/A, respectively. There was no significant difference between Cutlessapplied alone at 0.25 LB AI/A and the tank mix on this observation date.Likewise, no differences were noted 29 days after the firstapplications.

By 13 days after the June 27 application, the low rate tank mix gavesignificantly better color, density and quality compared with Primoapplied alone at 2× the tank mix rate. This tank mix rate also gavebetter color and density than Cutless applied alone at an 0.25 LB AI/A.Differences between the low rate tank mix and the materials appliedalone at 2× the respective tank mix rates had largely disappeared by 32days after the second application.

In summary, Primo+Cutless applied to Tifway (419) Bermudagrass at0.05+0.125 provided significantly better turf color, density and qualitythan either material applied alone at 2× the respective tank mix rates(Primo 0.1, Cutless 0.25 LB AI/A) in selected ratings made 13 days afterapplication. Differences between tank mix and single treatments largelydisappeared by 29 to 32 days after application. This trial indicatesthat tank mix applications of Primo+Cutless at rates substantially lowerthan those recommended for either material applied alone will provide arelatively rapid improvement and good turfgrass color, density andquality.

EXAMPLE 3

Tifway (419) Bermudagrass growing on a nursery area in South Carolinawas treated with Cutless 50W and Primo Maxx 1EC either singly or tankmixed to determine growth regulator activity. Primo was applied alone at0.05 and 0.1 LB AI/A, Cutless was applied alone at 0.125 and 0.25 LBAI/A, and Primo+Cutless were applied at 0.05+0.125 and 0.1+0.25 LB AI/A.Plot size was 6′×12′ with four replications. Two applications with a CO₂back-pack sprayer were made, occurring on June 13 and July 9. Plotsreceived approximately 0.25 inches or irrigation on each treatment datewithin 8 hours but not sooner than 4 hours after treatment. Ratings toevaluate performance have included injury (0–10 with 0=No injury,10=Death), color (plus or minus 100 with 100=Color of untreated, plus100=Darker green than untreated, minus 100=Lighter green thanuntreated), density (0–10 with 0=Bare ground, 10=Maximum potentialdensity), quality (0–9 with 0=Poor quality, 9=Maximum potentialquality), growth inhibition (percentage estimated), and scalping(percentage estimated). The results are presented in Table 3 below.

TABLE 3 Evaluation Date 20Jun02 27Jun02 27Jun02 27Jun02 27Jun02Evaluation Type* COLOR COLOR DENS QUAL GRINHIB Eval Unit/Scale* % VISUAL% VISUAL 0–10SCAL 0–9SCAL % VISUAL Trt-Eval Interval 7DAAA 14DAAA 14DAAA14DAAA 14DAAA Trt Appl Treatment Form Fm Ra Timing/ No Code Name* ConcDs* Rate Un* Dev Stg 1 A PRIMO 1 EC 0.05 LB AI/A JUNE 92.5 bc 121.3 a9.88 a 9.00 a 45.0 a A CUTLESS 50 WP 0.125 LB AI/A JUNE B PRIMO 1 EC0.05 LB AI/A JULY B CUTLESS 50 WP 0.125 LB AI/A JULY 2 A PRIMO 1 EC 0.1LB AI/A JUNE 77.5 d 120.0 a 9.38 ab 8.63 a 50.0 a A CUTLESS 50 WP 0.25LB AI/A JUNE B PRIMO 1 EC 0.1 LB AI/A JULY B CUTLESS 50 WP 0.25 LB AI/AJULY 3 A PRIMO 1 EC 0.05 LB AI/A JUNE 98.8 a 105.0 d 7.88 d 7.25 c 8.8 cB PRIMO 1 EC 0.05 LB AI/A JULY 4 A PRIMO 1 EC 0.1 LB AI/A JUNE 87.5 c111.3 c 8.75 bc 8.00 b 26.3 b B PRIMO 1 EC 0.1 LB AI/A JULY 5 A CUTLESS50 WP 0.125 LB AI/A JUNE 98.8 a 105.0 d 8.13 cd 7.38 c 11.3 c B CUTLESS50 WP 0.125 LB AI/A JULY 6 A CUTLESS 50 WP 0.25 LB AI/A JUNE 96.3 ab115.0 b 8.88 b 8.50 a 30.0 b B CUTLESS 50 WP 0.25 LB AI/A JULY 7UNTREATED 100.0 a 100.0 e 6.88 e 6.63 d 0.0 d LSD (P = .05) 5.13 3.590.673 0.495 6.31 CV 3.71 2.18 5.31 4.21 17.37 Replicate F 1.875 1.8311.101 0.938 5.192 Replicate Prob (F) 0.1700 0.1777 0.3742 0.4431 0.0093Treatment F 22.200 45.000 19.551 26.571 78.560 Treatment Prob (F) 0.00010.0001 0.0001 0.0001 0.0001 Evaluation Date 09Jul02 09Jul02 09Jul0209Jul02 Evaluation Type* COLOR DENS QUAL CUT Eval Unit/Scale* % VISUAL0–10SCAL 0–9SCAL % VISUAL Trt-Eval Interval 26DAAA 26DAAA 26DAAA 26DAAATrt Appl Treatment Form Fm Ra Timing/ No Code Name* Conc Ds* Rate Un*Dev Stg 1 A PRIMO 1 EC 0.05 LB AI/A JUNE 118.8 b 8.63 ab 7.88 b 1.3 d ACUTLESS 50 WP 0.125 LB AI/A JUNE B PRIMO 1 EC 0.05 LB AI/A JULY BCUTLESS 50 WP 0.125 LB AI/A JULY 2 A PRIMO 1 EC 0.1 LB AI/A JUNE 127.5 a9.50 a 8.75 a 0.0 d A CUTLESS 50 WP 0.25 LB AI/A JUNE B PRIMO 1 EC 0.1LB AI/A JULY B CUTLESS 50 WP 0.25 LB AI/A JULY 3 A PRIMO 1 EC 0.05 LBAI/A JUNE 101.3 e 6.50 c 5.88 e 37.5 b B PRIMO 1 EC 0.05 LB AI/A JULY 4A PRIMO 1 EC 0.1 LB AI/A JUNE 107.5 d 6.75 c 6.63 cd 21.3 c B PRIMO 1 EC0.1 LB AI/A JULY 5 A CUTLESS 50 WP 0.125 LB AI/A JUNE 101.3 e 6.63 c6.25 de 41.3 b B CUTLESS 50 WP 0.125 LB AI/A JULY 6 A CUTLESS 50 WP 0.25LB AI/A JUNE 112.5 c 7.50 bc 7.13 c 5.0 d B CUTLESS 50 WP 0.25 LB AI/AJULY 7 UNTREATED 100.0 6.13 c 4.63 f 75.0 LSD (P = .05) 4.77 1.324 0.5529.99 CV 2.92 12.08 5.52 25.98 Replicate F 3.087 1.691 1.101 3.809Replicate Prob (F) 0.0534 0.2045 0.3745 0.0283 Treatment F 41.885 7.87552.942 66.579 Treatment Prob (F) 0.0001 0.0003 0.0001 0.0001 EvaluationDate 29Jul02 29Jul02 29Jul02 29Jun02 29Jul02 Evaluation Type* COLOR DENSQUAL GRINHIB CUT Eval Unit/Scale* % VISUAL 0–10SCAL 0–9SCAL % VISUAL %VISUAL Trt-Eval Interval 20DAAB 20DAAB 20DAAB 20DAAB 20DAAB Trt ApplTreatment Form Fm Ra Timing/ No Code Name* Conc Ds* Rate Un* Dev Stg 1 APRIMO 1 EC 0.05 LB AI/A JUNE 122.5 a 8.50 a 7.88 a 21.3 b 2.5 d ACUTLESS 50 WP 0.125 LB AI/A JUNE B PRIMO 1 EC 0.05 LB AI/A JULY BCUTLESS 50 WP 0.125 LB AI/A JULY 2 A PRIMO 1 EC 0.1 LB AI/A JUNE 120.0 a8.13 ab 7.50 ab 41.3 a 0.0 d A CUTLESS 50 WP 0.25 LB AI/A JUNE B PRIMO 1EC 0.1 LB AI/A JULY B CUTLESS 50 WP 0.25 LB AI/A JULY 3 A PRIMO 1 EC0.05 LB AI/A JUNE 102.5 b 6.25 d 6.00 d 3.8 cd 21.3 b B PRIMO 1 EC 0.05LB AI/A JULY 4 A PRIMO 1 EC 0.1 LB AI/A JUNE 107.5 b 6.75 cd 6.13 cd10.0 c 15.0 bc B PRIMO 1 EC 0.1 LB AI/A JULY 5 A CUTLESS 50 WP 0.125 LBAI/A JUNE 105.0 b 7.38 bc 6.88 bc 10.0 c 11.3 c B CUTLESS 50 WP 0.125 LBAI/A JULY 6 A CUTLESS 50 WP 0.25 LB AI/A JUNE 121.3 a 8.50 a 7.88 a 20.0b 0.0 d B CUTLESS 50 WP 0.25 LB AI/A JULY 7 UNTREATED 102.5 b 5.00 e4.50 e 0.0 d 50.0 a LSD (P = .05) 5.56 0.899 0.755 7.46 7.98 CV 3.358.39 7.6 33.07 37.61 Replicate F 6.362 5.268 4.662 0.697 1.072 ReplicateProb (F) 0.0040 0.0087 0.0140 0.5660 0.3857 Treatment F 24.234 18.59323.492 30.543 43.433 Treatment Prob (F) 0.0001 0.0001 0.0001 0.00010.0001 Evaluation Date 14Aug02 14Aug02 14Aug02 14Aug02 14Aug02Evaluation Type* COLOR DENS QUAL INJURY GRINHIB Eval Unit/Scale* %VISUAL 0–10SCAL 0–9SCAL 0–10SCAL % VISUAL Trt-Eval Interval 36DAAB36DAAB 36DAAB 36DAAB 36DAAB Trt Appl Treatment Form Fm Ra Timing/ NoCode Name* Conc Ds* Rate Un* Dev Stg 1 A PRIMO 1 EC 0.05 LB AI/A JUNE120.0 a 8.50 a 7.88 a 0.00 b 12.5 b A CUTLESS 50 WP 0.125 LB AI/A JUNE BPRIMO 1 EC 0.05 LB AI/A JULY B CUTLESS 50 WP 0.125 LB AI/A JULY 2 APRIMO 1 EC 0.1 LB AI/A JUNE 115.0 ab 7.00 c 6.88 b 2.63 a 31.3 a ACUTLESS 50 WP 0.25 LB AI/A JUNE B PRIMO 1 EC 0.1 LB AI/A JULY B CUTLESS50 WP 0.25 LB AI/A JULY 3 A PRIMO 1 EC 0.05 LB AI/A JUNE 105.0 cd 7.25 c6.88 b 0.00 b 2.5 d B PRIMO 1 EC 0.05 LB AI/A JULY 4 A PRIMO 1 EC 0.1 LBAI/A JUNE 110.0 bc 7.75 bc 7.50 ab 0.00 b 8.8 bc B PRIMO 1 EC 0.1 LBAI/A JULY 5 A CUTLESS 50 WP 0.125 LB AI/A JUNE 105.0 cd 7.38 c 7.25 ab0.00 b 3.8 cd B CUTLESS 50 WP 0.125 LB AI/A JULY 6 A CUTLESS 50 WP 0.25LB AI/A JUNE 116.3 ab 8.13 ab 7.63 ab 0.00 b 13.8 b B CUTLESS 50 WP 0.25LB AI/A JULY 7 UNTREATED 100.0 d 6.25 d 6.00 c 0.00 b 0.0 d LSD (P =.05) 6.89 0.708 0.783 0.623 5.77 CV 4.21 6.39 7.38 111.74 37.49Replicate F 2.806 2.253 0.600 1.000 2.289 Replicate Prob (F) 0.06910.1170 0.6233 0.4155 0.1130 Treatment F 9.719 9.786 5.657 22.424 29.526Treatment Prob (F) 0.0001 0.0001 0.0019 0.0001 0.0001

Evaluations 14 days after the June 13 application showed significantly(P=0.05, Duncan's new MRT) better color, density and overall growthinhibition with Primo+Cutless tank mixed at 0.05+0.125 LB AI/A than withPrimo alone at 0.1 LB AI/A or Cutless alone at 0.25 LB AI/A. By 26 daysafter the first application, the low rate tank mix provided bettercolor, density, quality and scalping reduction than Primo applied aloneat 0.1 LB AI/A. Cutless applied alone at 0.25 LB AI/A was notsignificantly different from the low rate tank mix with any of theevaluation criteria.

By 20 days after the second application made July 9, the low rate tankmix gave significantly better color, density, quality, overall growthinhibition and scalping reduction than Primo applied alone at 0.1 LBAI/A. Ratings made 36 days after the second application showed few, ifany, significant differences between the low rate tank mix and eithermaterial applied alone at 2× the respective tank mix rate.

In summary, Primo+Cutless applied to Tifway (419) Bermudagrass at0.05+0.125 provided significantly better turf color, density and qualitythan either material applied alone at 2× the respective tank mix rates(Primo 0.1, Cutless 0.25 LB AI/A) in ratings made 14 to 20 days afterapplication. Differences between tank mix and single treatments largelydisappeared by 26 to 36 days after application. This trial indicatesthat tank mix applications of Primo+Cutless at rates substantially lowerthan those recommended for either material applied alone will provide arelatively rapid regulation and good turfgrass color, density andquality.

EXAMPLE 4

The general procedure of Example 1 was repeated, except adding to theprotocol testing of combinations of paclobutrazol and trinexepac-ethyl.The application regimen for each plot is outlined below.

Plot PGR regimen 1 Primo + Cutless 0.05 + 0.125 lb AI/A 2 Primo + TGR0.05 + 0.125 lb AI/A 3 Primo 0.05 lb AI/A 4 Primo 0.1 lb AI/A 5 Cutless0.125 lb AI/A 6 Cutless 0.25 lb AI/A 7 TGR 0.125 lb AI/A 8 TGR 0.25 lbAI/A 9 Untreated (check)

Applications were made on August 20. The results evidenced thatsurprisingly beneficial treatments of turfgrass were achieved throughcombinations of trinexapac-ethyl with paclobutrazol and withflurprimidol, in a fashion similar- to Examples 1–3 above.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly the preferred embodiment has been shown and described and that allchanges and modifications that come within the spirit of the inventionare desired to be protected. In addition, all patents and otherpublications cited herein are hereby incorporated by reference in theirentirety as if each had been individually incorporated by reference andfully set forth.

1. A method for regulating plant growth, comprising: applying to a planta Class A gibberellin biosynthesis inhibitor; and applying to the planta Class B gibberellin biosynthesis inhibitor; wherein said Class A andClass B gibberellin synthesis inhibitors exhibit synergism in regulatinggrowth of the plant.
 2. A method according to claim 1, wherein: saidClass A gibberellin synthesis inhibitor is encompassed by the formula:

wherein A is an —OR₂ or —NR₃ R₄ radical, R is C₃–C₆ cycloalkyl, R₂ R₃and R₄ are each independently hydrogen, C₁–C₆ alkyl, C₁–C₆ haloalkyl,C₂–C₁₀ alkoxyalkyl, C₂–C₁₀ alkylthioalkyl, C₃–C₆ alkenyl, which isunsubstituted or substituted by halogen, C₁–C₄ alkoxy or C₁–C₄alkylthio; C₃–C₆ alkynyl; phenyl or C₁–C₆ aralkyl, wherein the phenylnucleus is unsubstituted or substituted by halogen, C₁–C₄ alkyl, C₁–C₄alkoxy, C₁–C₄ haloalkyl, nitro or cyano; one of R₃ and R₄ is methoxy; orR₃ and R₄, together with the nitrogen atom to which they are attached,form a 5- or 6-membered heterocyclic ring system which may contain anadditional oxygen or sulfur atom in the ring; and the metal or ammoniumsalts thereof.
 3. A method according to claim 2, wherein the Class Agibberellin synthesis inhibitor is trinexapac-ethyl.
 4. A methodaccording to claim 1, wherein the Class B gibberellin synthesisinhibitor is encompassed by the formula:

wherein R₅ is alkenyl, alkynyl or optionally substituted aralkyl; Y is═N— or ═CH—; R₆ is cycloalkyl, alkyl or haloalkyl; and R₇ is hydrogen,methyl or alkenyl, or an ester, an ether, an acid addition salt or ametal complex thereof.
 5. A method according to claim 4, wherein theClass B gibberellin synthesis inhibitor is paclobutrazol.
 6. A methodaccording to claim 1, wherein: the Class B gibberellin synthesisinhibitor is encompassed by the formula:

wherein R₈ is 2-pyrazinyl, 3-pyridyl, or 5-pyrimidinyl; R₉ is phenyl,pyridyl, C₁–C₁₂ alkyl, or C₃–C₈ cycloalkyl; R₁₀ istrifluoromethoxyphenyl, tetrafluoroethoxyphenyl,pentafluoroethoxyphenyl, 3,4-(difluoromethylenedioxy)phenyl, or2,2,4,4-tetrafluoro-1,3-benzodioxanyl; X is hydrogen, hydroxy, loweralkoxy, lower alkylthio, or lower alkanoyloxy; or an acid addition saltthereof.
 7. A method according to claim 6, wherein the Class Bgibberellin synthesis inhibitor is flurprimidol.
 8. A method accordingto any of claims 1–7, wherein the Class A and Class B gibberellinbiosynthesis inhibitors are applied together.
 9. A method according anyof claims 1–7, wherein the Class A and Class B gibberellin biosynthesisinhibitors are applied separatetly.
 10. A method according to claim 1,wherein the plant is turfgrass.
 11. A method according to claim 10,wherein the Class A gibberellin biosynthesis inhibitor istrinexepac-ethyl, and wherein the trinexepac-ethyl is applied at a levelof about 0.02 to about 0.7 pounds of active ingredient per acre.
 12. Amethod according to claim 11, wherein the Class B gibberellinbiosynthesis inhibitor is flurprimidol, and wherein the flurprimidol isapplied at a level of about 0.05 to about 1.5 pounds of activeingredient per acre.
 13. A method according to claim 11, wherein theClass B gibberellin biosynthesis inhibitor is paclobutrazol, and whereinthe paclobutrazol is applied at a level of about 0.05 to 1.0 pounds ofactive ingredient per acre.
 14. A method according to any of claims10–13, wherein the Class A and Class B gibberellin biosynthesisinhibitors are applied together.
 15. A method according to any of claims10–13, wherein the Class A and Class B gibberellin biosynthesisinhibitors are applied separately.
 16. A method according to claim 14,wherein the turfgrass comprises one or more grasses selected from asBahiagrass (Paspalum notatum); Bermudagrass (Cynodon dactylon);Buffalograss (Buchloe dactyloides); Carpetgrass (Axonopus affinis);Centipedegrass (Eremochloa ophiuroides); Kikuyugrass (Pennisetumcladestinum); Seashore paspalum (Paspalum vaginatum); St. Augustinegrass(Stenotaphrum secundatum); Zoysiagrass (Zoysia matrella (japonica));Annual ryegrass (Lolium multiflorum); Bentgrass (Agrostis spp.); Fescue(Festuca spp.); Kentucky bluegrass (Poa pratensis); Perennial ryegrass(Lolium perenne); and Poa annua.
 17. A method according to claim 14,wherein the turfgrass comprises one or more grasses selected fromBermudagrass (Cynodon dactylon); Annual ryegrass (Lolium multiflorum);Bentgrass (Agrostis spp.); Kentucky bluegrass (Poa pratensis); andPerennial ryegrass (Lolium perenne).
 18. A composition for regulatingplant growth, comprising: a Class A gibberellin biosynthesis inhibitor;and a Class B gibberellin biosynthesis inhibitor; wherein saidbiosynthesis inhibitors exhibit synergism in the regulation of plantgrowth.
 19. A composition according to claim 18, wherein: said Class Agibberellin synthesis inhibitor is encompassed by the formula:

wherein A is an —OR₂ or —NR₃, R₄ radical, R is C₃–C₆ cycloalkyl, R₂, R₃and R₄ are each independently hydrogen, C₁–C₆ alkyl, C₁–C₆ haloalkyl,C₂–C₁₀ alkoxyalkyl, C₂–C₁₀ alkylthioalkyl, C₃–C₆ alkenyl, which isunsubstituted or substituted by halogen, C₁–C₄ alkoxy or C₁–C₄alkylthio; C₃–C₆ alkynyl; phenyl or C₁–C₆ aralkyl, wherein the phenylnucleus is unsubstituted or substituted by halogen, C₁–C₄ alkyl, C₁–C₄alkoxy, C₁–C₄ haloalkyl, nitro or cyano; one of R₃ and R₄ is methoxy; orR₃ and R₄, together with the nitrogen atom to which they are attached,form a 5- or 6-membered heterocyclic ring system which may contain anadditional oxygen or sulfur atom in the ring; and the metal or ammoniumsalts thereof.
 20. A composition according to claim 18, wherein theClass A gibberellin synthesis inhibitor is trinexapac-ethyl.
 21. Acomposition according to claim 18, wherein the Class B gibberellinsynthesis inhibitor is encompassed by the formula:

wherein R₅ is alkenyl, alkynyl or optionally substituted aralkyl; Y is═N— or ═CH—; R₆ is cycloalkyl, alkyl or haloalkyl; and R₇ is hydrogen,methyl or alkenyl, or an ester, an ether, an acid addition salt or ametal complex thereof.
 22. A composition according to claim 21, whereinthe Class B gibberellin synthesis inhibitor is paclobutrazol.
 23. Acomposition according to claim 18, wherein: the Class B gibberellinsynthesis inhibitor is encompassed by the formula:

wherein R₈ is 2-pyrazinyl, 3-pyridyl, or 5-pyrimidinyl; R₉ is phenyl,pyridyl, C₁–C₁₂ alkyl, or C₃–C₈ cycloalkyl; R₁₀ istrifluoromethoxyphenyl, tetrafluoroethoxyphenyl,pentafluoroethoxyphenyl, 3,4-(difluoromethylenedioxy)phenyl, or2,2,4,4-tetrafluoro-1,3-benzodioxanyl; X is hydrogen, hydroxy, loweralkoxy, lower alkylthio, or lower alkanoyloxy; or an acid addition saltthereof.
 24. A composition according to claim 23, wherein the Class Bgibberellin synthesis inhibitor is flurprimidol.
 25. A compositionaccording to claim 18, wherein: the Class A gibberellin biosynthesisinhibitor is trinexepac-ethyl, and wherein the trinexepac-ethyl ispresent in the composition at a concentration of about 0.5 to about 3pounds per gallon.
 26. A composition according to claim 18, wherein: theClass B gibberellin biosynthesis inhibitor is flurprimidol, and whereinthe flurprimidol is present in the composition at a concentration ofabout 0.5 to about 3 pounds per gallon.
 27. A composition according toclaim 18, wherein: the Class B gibberellin biosynthesis inhibitor ispaclobutrazol, and wherein the paclobutrazol is present in thecomposition at a level of about 0.5 to about 3 pounds per gallon.
 28. Acomposition according to claim 26, adapted for application to turfgrass.29. A composition according to claim 27, adapted for application toturfgrass.
 30. A method according to claim 28 or 29, wherein theturfgrass comprises one or more grasses selected from Bermudagrass(Cynodon dactylon); Annual ryegrass (Lolium multiflorum); Bentgrass(Agrostis spp.); Kentucky bluegrass (Poa pratensis); and Perennialryegrass (Lolium perenne).
 31. A composition according to claim 18,which comprises an aqueous carrier.
 32. A composition according to claim18, wherein the Class A and Class B gibberellin biosynthesis inhibitorsare present in a molar ratio of about 1:0.625 to about 1:5.